The present invention relates generally to subsea wells having multiple tubing strings or bores extending into the bore hole from a wallhead and with a riser extending to the water surface, and more particularly, to a bore selector disposed between the riser and wellhead for providing selective access between the riser and one of the individual bores.
Subsea wells with multiple bores have one or more tubing or production strings suspended from a wellhead. A riser extends from the wellhead to a platform at the surface. Oftentimes it is necessary to have access to individual bores for extending a wire line tool from the surface into one of the bores. The riser includes multiple strings of riser pipe extending to the surface typically with individual riser strings for each bore. However, individual riser strings are very expensive. Many times these risers must be specially built to allow access to each of the individual bores.
A dual bore selector selects either the bore for production or the bore to the annulus in a dual bore completion. The dual bore selector is either connected above a tubing hanger running tool or is tied back into the christmas tree, depending on whether you are performing a workover. A specialty riser is constructed which includes two casing strings side by side to tie back and communicate with the dual bores. The riser is used to perform the initial completion and the workover. Such specialty risers are quite expensive and specialty risers in 45 foot sections for deep water may cost millions of dollars just for the risers. Thus, it is preferred to only have one riser string extending to the surface thereby eliminating the other string to reduce cost.
U.S. Pat. No. 4,770,247 discloses a multiple bore well having a riser with a bore selector. The selector is connected at its lower end to a sub sea wellhead supporting multiple tubing strings for completion and workover operations. The selector is connected at its upper end to the lowest section of the riser string extending to the surface. The selector includes an upper tubular member having a single bore in flow communication with the riser string, a lower member having multiple bores which align with the multiple bores of the subsea wellhead, and an intermediate section having a rotary portion which communicates with the single upper born and selectively communicates with each of the individual lower multiple bores as the intermediate section is rotated.
Various prior art patents disclose flowline switches or selectors. U.S. Pat. Nos. 4,133,418; 4,223,700; 4,291,724; and 5,129,459 disclose a flowline switch or selector having a housing with a rotor mounted therewithin to rotate a tubular passageway extending through the rotor so as to connect an upper port to one of a plurality of ports at its lower end. U.S. Pat. No. 5,129,459 reciprocates and indexes the rotor tube up and down thereby rotating the tube between various lower ports as the rotor tube rotates within the housing.
There are also several different types of diverters and diverter valves for selecting between two conduits. U.S. Pat. Nos. 2,752,944 and 3,664,376 illustrate push-pull type diverters with a horizontally reciprocating piston; U.S. Pat. Nos. 1,951,434 and 4,252,149 disclose flapper type diverters having pivoting diverter members; and U.S. Pat. Nos. 2,586,144 and 3,834,418 show diverters having flexible members which are selectively moved between two conduits.
The present invention overcomes the deficiencies of the prior art.